#define _CRT_SECURE_NO_WARNINGS 1
#include <stdio.h>

int rec(int n)
{
	if (n <= 2)
		return 1;
	else
		return rec(n - 1) + rec(n - 2);
}

int main()
{
	int n = 0;
	
		scanf("%d", &n);
		printf("%d", rec(n));
		return 0;
		
}

